Regression: spaceship (<=>) on backed enum cases — VM still inverts Zend signs (re-#9796, Zend/zend_enum.c)

[PurHur]

Category

language · php-src-strict

Problem

#9796 closed but VM still diverges from Zend on spaceship (<=>) for backed enum cases. Docker verification 2026-06-20:

Expression	Zend PHP 8.2	php bin/vm.php
E::A <=> E::B (A=1, B=2)	int(1)	int(-1) ❌
E::A <=> 1	int(1)	int(0) ❌
E::A <=> 'x'	int(1)	int(-1) ❌

Distinct from #9476 (LLVM migration): this is compare semantics in VM/JIT shared guards, not routing SpaceshipCompareJit to PHP.

php-src reference

• php/php-src Zend/zend_enum.c — zend_compare_enum
• php/php-src Zend/zend_operators.c — compare_function spaceship dispatch

Repro

test/repro/maintainer_spaceship_enum.php:

<?php
declare(strict_types=1);
enum E: int { case A = 1; case B = 2; }
var_dump(E::A <=> E::B);
var_dump(E::A <=> 1);
var_dump(E::A <=> 'x');

./script/docker-exec.sh -- bash -lc 'source script/php-env.sh
php test/repro/maintainer_spaceship_enum.php
echo VM:
php bin/vm.php test/repro/maintainer_spaceship_enum.php
'

Scope

Area	Files
VM	lib/VM/CompareSupport.php or enum compare path
JIT	shared compare guards — must agree with VM
Tests	test/compliance/cases/language/enum_spaceship.phpt

Done when

• All three var_dump lines match Zend output on VM
• JIT agrees when in scope
• ./script/ci-fast.sh --filter enum_spaceship green

Links

• Re-Language: spaceship (<=>) on backed enum cases — wrong sign vs Zend backing-value compare (Zend/zend_enum.c) #9796 · php-in-php: JIT SpaceshipCompareJit — route <=> through CompareJitHelper PHP not ~1.2k-line LLVM (#1492) #9476 · North star Epic: Self-host critical path — compiler compiles itself (M3→M5) #1492

[PurHur]

claim: cursor-agent-lane-a — starting this run (language scope: Zend/zend_enum.c spaceship compare; stdlib label appears mis-tagged)

[PurHur]

claim released: verified fixed on master — repro and enum_spaceship compliance (3/3) green; VM output matches Zend (int(1) ×3).

[PurHur]

claim: cursor-agent-lane-a — starting this run (verify #10203 green on master; add maintainer repro guard + close stale filing)

[PurHur]

Verified fixed on master (lane A audit 2026-06-20): maintainer repro + enum_spaceship compliance 3/3 green; VM matches Zend (int(1) for all three probes).

[PurHur]

Merged via #10207.

Root cause: Stale regression filing — enum spaceship parity was already fixed on master (re-#9796). VM/JIT no longer compare enum cases as backing scalars for <=>.

This PR: Added EnumSpaceshipMaintainerReproTest guarding test/repro/maintainer_spaceship_enum.php on VM + JIT.

Verification:

source script/php-env.sh
php test/repro/maintainer_spaceship_enum.php
php bin/vm.php test/repro/maintainer_spaceship_enum.php
php bin/jit.php test/repro/maintainer_spaceship_enum.php
php vendor/bin/phpunit test/unit/EnumSpaceshipMaintainerReproTest.php

All output int(1) / OK (2 tests).

[PurHur]

Merged via #15937.

Root cause: var_dump(E::A <=> E::B) wired TYPE_ARG_SEND to a hoisted enum-case temp (E::B) instead of the spaceship result slot. precedingInlineCallArgProducersBeforeCfgOp skipped immediate comparison preludes when inlineCallArgProducerFeedsConsumer was false (distinct php-cfg temps).

Fix: Final compileCallArgSends pass prefers the immediate spaceship/relational CFG prelude; keep comparison producers when call arg is a dead inline temp.

php bin/vm.php test/repro/maintainer_spaceship_enum.php
vendor/bin/phpunit --filter EnumSpaceshipMaintainerReproTest